Platynectes (Platynectes) decemnotatus ( Aubé, 1838 )

Gustafson, Grey T., Short, Andrew E. Z. & Miller, Kelly B., 2016, New species of diving beetles in the subgenus Platynectes s. str. from the Guiana Shield (Coleoptera: Dytiscidae: Agabinae), Acta Entomologica Musei Nationalis Pragae 56 (1), pp. 79-102: 82-85

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Platynectes (Platynectes) decemnotatus ( Aubé, 1838 )


Platynectes (Platynectes) decemnotatus ( Aubé, 1838)  

( Figs 2 View Figs 1–6 , 10 View Figs 7–13 , 15 View Fig , 17, 18 View Figs 16–19 )

Agabus decemnotatus Aubé, 1838: 319   [original description].

Platynectes decemnotatus: SHARP (1882)   : 538 [new combination by indication to species 768 in Group 3].

Platynectes (Hypoplatynectes) decemnotatus: GUÉORGUIEV (1972)   : 39 [new combination; synonymy by VAZIRANI (1976): 170].

Platynectes (Platynectes) decemnotatus: VAZIRANI (1976)   : 170 [new status].

Type material examined. LECTOTYPE (here designated): ♀ ( MNHN), by present designation: “Cateneur [?] Cayenne” [green and roundish handwritten label], “10 notatus Aubé” [white and handwritten label], “ Lectotype Agabus decemnotatus Aubé Gustafson, Short & Miller   des. 2016” [red printed label].

Additional material examined (91 spec.). FRENCH GUIANA: “ KAW MOUNTAIN RESERVE, Kaw River Boat launch, N4°29′54.8″ W52°03′05.6″, 20 m, 8–18.ii.2005, leg. KB Miller ” (2 spec. MSBA) GoogleMaps   ; same as previous except: N4°32′57.8″ W52°12′49.7″, 286 m, forest pools nr Amazone Lodge (2 spec. MSBA) GoogleMaps   . SURINAME: SIPALIWINI DISTRICT: CSNR: Tafelberg Summit, nr Augustus Creek Camp , N3°55.600′ W56°11.300′, 600 m, 17.viii.2013, leg. Short & Bloom, small stream on trail to Caiman Creek Camp, SR 13-0817-02 A, SEMC1080669 View Materials , SEMC1080670 View Materials , SEMC1080671 View Materials , SEMC1080675 View Materials , SEMC1080681 View Materials , SEMC1080682 View Materials (6 spec. SEMC) GoogleMaps   ; same as previous except: nr

Caiman Creek Camp, N3°53.942′ W56°10.849′, 733 m, 18.viii.2013, leg. Short & Bloom, small streams with lots of plants & leaf litter, SR13-0818-03 A, SEMC1233862 View Materials , SEMC1233863 View Materials (2 spec. SEMC) GoogleMaps   ; same as previous except: 19.viii.2013, pools in forest, SR13-0819-05B, SEMC1233914 View Materials (1 spec. SEMC)   ; same as previous except: forest detrital pools, SR13-0819-05C, SEMC0966146 View Materials , SEMC0966147 View Materials , SEMC1080493 View Materials (3 spec. SEMC)   ; same district except: Camp 4 (high), Kasikasima , N2°58.613′ W55°24.683′, 400 m, 24.iii.2012, leg. Short, main seepage area, SR12-0324-01C 2012 CI-RAP Survey, SEMC1087462 View Materials , SEMC1087466 View Materials , SEMC1088132 View Materials SEMC1088137 View Materials (8 spec. SEMC) GoogleMaps   ; same as previous except:rocky pools at base of seep, SR12-0324-01D 2012 CI-RAP survey, SEMC1088360 View Materials , SEMC1088362 View Materials , SEMC1088366 View Materials SEMC1088369 View Materials , SEMC1088373 View Materials , SEMC1088376 View Materials SEMC1088382 View Materials , SEMC1088384 View Materials , SEMC1088386 View Materials , SEMC1088387 View Materials , SEMC1088389 View Materials SEMC1088392 View Materials (21 spec. SEMC)   ; same district except: Camp 2, on Sipaliwini River , N2°10.973′ W56°47.235′, 210 m, 29–30.viii.2010, leg. Short & Kadose, inselberg, SR10- 0829-01 A 2010 CI-RAP survey, SEMC0913037 View Materials SEMC0913039 View Materials , SEMC0913041 View Materials SEMC0913045 View Materials , SEMC0914529 View Materials , SEMC0914532 View Materials , SEMC0914535 View Materials SEMC0914540 View Materials , SEMC0914542 View Materials , SEMC0914544 View Materials , SEMC0914545 View Materials , SEMC0914547 View Materials , SEMC0914549 View Materials , SEMC0914551 View Materials , SEMC0914552 View Materials , SEMC0914554 View Materials , SEMC0914555 View Materials , SEMC0914557 View Materials SEMC091559 View Materials , SEMC0914561 View Materials SEMC0914563 View Materials , SEMC0914567 View Materials , SEMC0914568 View Materials , SEMC0914570 View Materials SEMC0914575 View Materials , SEMC0914577 View Materials , SEMC0914580 View Materials , SEMC0914581 View Materials , SEMC0914586 View Materials , SEMC0914587 View Materials , SEMC0914858 View Materials (45 spec. SEMC, NZCS). “Amer mer.” [white handwritten label], “ decemnotatus Aubé   ” [white handwritten label] (1 spec. MNHN) GoogleMaps   .

Diagnosis. Larger in size (6.6–7.7 mm in length), body robust and broadly oval, elytron with five well-demarcated yellow spots.

Redescription. Size. Male: TL = 7.2–7.7 mm, TL-h = 6.6–7.0 mm, TW = 4.32–4.7 mm; female: TL = 6.6–7.7 mm, TL-h = 6.2–7.2 mm, TW = 4.1–4.8 mm.

Body robust, and broad, broadly oval, lateral margins evenly curved and continuous between pronotum and elytron ( Fig. 2 View Figs 1–6 ).

Coloration ( Fig. 2 View Figs 1–6 ). Head orange grading into diffuse, light yellow region medially on frons and testaceous to black mediad and posteriad of eyes, in some specimens extending anteriorly around eye to lateral margin of frons. Pronotum broadly black or testaceous medially along anterior and posterior margins, black regions meeting medially in lighter, testaceous transverse band; posterolateral margins of pronotum narrowly black, lateral surfaces yellow, extending medially to dark region; scutellum testaceous. Elytron dark testaceous, with small, diffuse pale region at humeral angle and five well-demarcated yellow spots, one parascutellar, one slightly anterior of middle near suture, one slightly posterior of middle near lateral margin, and one anteapically which, in some specimens, extends anteriorly and posteriorly along margins. Appendages of head, legs and ventral surfaces, including elytral epipleuron, pale orange to reddish, somewhat darker on thoracic sterna and metacoxae; last abdominal tergite yellow.

Structure and sculpture. Head broad and short, anterior clypeal margin broadly rounded; anterior surface of frons and clypeus with fine, dense punctation, posterior surface of head with fine microreticulation of irregular cells, most cells also with fine punctures. Pronotum broad and short; lateral bead distinct and broad, evenly curved, about width of antennomere V; surface shiny, covered with fine microreticulation of large, irregular cells, cells with fine punctures, additional punctation consisting of a row of large coarse punctures on anterior and posterior margins, punctures separated by ca. 1–2× diameter of a puncture anteriorly, ca. 1–3× diameter of a puncture posteriorly, absent medially. Elytron broad, lateral margins evenly curved to slightly angulate apex, lateral epipleural carina distinctly visible throughout length; surface covered with weakly impressed, but distinct microreticulation of large irregular cells, most cells also with fine punctures; elytral epipleuron slender, evenly tapered to apex. Prosternum medially moderately long, longitudinally swollen; prosternal process broad, lateral margins broadly curved to somewhat pointed apex, surface flat to slightly curved, smooth. Metaventrite with anterior process broad, with broadly curved emargination for reception of prosternal process; lateral wings broad, WC/WS = 4.5; surface smooth, weakly impressed reticulation composed of elongate cells, fairly even covering of fine punctation, punctures separated by ca. 1–2× diameter of a puncture. Fore- and midlegs slender, surfaces punctate, protibial apices with several spines about length of protarsomeres I+II; mesotibal apices with few spines shorter than length of mesotarsomeres I+II, mesotarsal spurs elongate slen- der, slightly sinuate, as long as mesotarsomeres I+II; metacoxae smooth, fine reticulation composed of round cells, fine and weakly impressed punctation present, punctures separated by ca. 3–4× metacoxal lines distinct, broadly divergent anteriorly; hind legs slender, smooth, metafemur with fine reticulation composed of elongate cells, almost imperceptible, weakly impressed punctation, few setigerous punctures on anterior surface of metatibia and metatarsomere I, metatrochanter apically spinous, metatibial spurs slender, longer than metatarsus I. Abdominal ventrites broad, smooth and unmodified, with fine reticulation composed of elongate cells, fine weakly impressed punctation, punctures separated by ca. 3–4× diameter of a single puncture.

Male genitalia ( Fig. 10 View Figs 7–13 ). Median lobe in left lateral view strongly curved, apex weakly expanded, strongly acute, dorsal surface covered in pores in apical 2/3; ventral groove in right lateral view strongly narrowed apically, greatly widened in basal 2/3.

Sexual dimorphism. There does not appear to be any noticeable sexual dimorphism aside from the normal pro- and mesotarsal dimorphism.

Variation. There is quite a bit of size variation, with some populations having very large and broad individuals, while others have smaller and somewhat more parallel-sided individuals. Differential diagnosis. Platynectes decemnotatus   is most similar to P. submaculatus   in terms of elytral maculation pattern, having five yellow well-demarcated spots on each elytron, but is much larger in body size (6.6–7.7 mm) and more broadly rounded ( Fig. 2 View Figs 1–6 ). The large size, broadly oval body form, with five well-demarcated yellow spots on each elytron should prevent its confusion with any other species within the P. submaculatus   group.

Natural history. This species has been collected in many stream and seep-associated habitats. Most collections are from small, forested streams with abundant detritus. A few collections were made in pools formed in or below seepages from granite inselbergs or other similar rocky outcrops ( Figs 17–18 View Figs 16–19 ).

Distribution. The species is currently known from French Guiana and Suriname ( Fig. 15 View Fig ).

Discussion. In a small box of historical Platynectes   specimens lent by the late Dr. Michel Brancucci from the Muséum national d’Histoire naturelle, Paris, several years ago L. Hendrich identified two historical specimens of P. decemnotatus   . According to the label data the one female should be a syntype from Aubé collection. As the number of syntypes is not specified in the original description, we designate here the lectotype to fix the identity of the species.


Museum National d'Histoire Naturelle


University of Kansas - Biodiversity Institute


University, National Zoological Collection of Suriname














Platynectes (Platynectes) decemnotatus ( Aubé, 1838 )

Gustafson, Grey T., Short, Andrew E. Z. & Miller, Kelly B. 2016

Platynectes (Platynectes) decemnotatus: VAZIRANI (1976)

VAZIRANI T. G. 1976: 170

Platynectes (Hypoplatynectes) decemnotatus: GUÉORGUIEV (1972)

VAZIRANI T. G. 1976: 170
GUEORGUIEV V. B. 1972: 39

Platynectes decemnotatus:

SHARP D. 1882: 538

Agabus decemnotatus Aubé, 1838: 319

AUBE C. 1838: 319